Inductance is the ability of a device to store energy in the form of a magnetic field. An inductor is an electronic component designed specifically to provide a controlled amount of inductances. Inductors generally consist of a length of wire wound around a solenoidal or toroidal shape. The inductance may be increased by placing a core with a high magnetic permeability within the core. Suitable materials such as iron, powdered iron and ferrite may be utilized. Commercially made inductors have values ranging from less than 1 microhenrys (μH) to about 10 Henrys (H). Small inductors have been used in radio-frequency tuned circuits and as radio-frequency chokes. Large inductors have been utilized at audio frequencies with the largest inductors being used as filter chokes in power supplies.
Coil-shaped inductors are used in tuned circuits for audio frequencies to the ultrahigh radio-frequency region. In the ultrahigh-frequency and microwave bands, short links of transmission lines can serve as inductors. Any length of line shorter than ¼ electrical wavelength short-circuited at the far end acts as an inductor. The same is true of a section of line between ¼ and ½ wavelength, with an open circuit at the far end.
A perfect inductor shows only inductive reactance, and no resistance. Such a perfect inductor exists only in theory and real inductors have some ohmic loss as well as reactance. Inductors have been utilized in semiconductor devices, and those skilled in the art continue to develop semiconductors with inductor assemblies having improved properties.
The present invention provides alternatives to the prior art.